The approach to add the rhev-h to rhev-m

I installed a rhev-h, but did not set the rhev-m information for rhev-h during the installing of rhev-h. Then I tried to add the rhev-h to rhev-m by from the 'hosts' panel, but always got the error message: Cannot add Host. Failed creating an SSH session with the host. Verify that the host is reachable (IP address, routable address etc.) and authentication parameters are correct (Username/Password, public-key etc.) You may refer to the rhevm.log file for further details.

But in fact, I could ssh to the rhev-h from rhev-m with both admin and root. What I can do to fix this?

By the way, I could configure the rhev-h manually to make the rhev-m detected rhev-h automatically.